98 3.4 liter misfire.

I have searched through past forums for help with this problem but nothing has fixed my misfire yet.
I got code 0306 for a cylinder 6 misfire. I went home and changed the coil packs, unhooked the battery and went back to get codes checked. It came back still as 0306 so I put a new spark plug in cylinder 6 but still the same issue. Based on the code the 2 other possible problems are a vacuum leak or a bad injector. I have checked all the hoses and they appear to be fine and I would really like to avoid putting in an injector if possible.
Any other solutions? Any help is appreciated.

 

I switched the coil packs around and still got a cylinder 6 misfire. I checked and there is spark to the plug. I also did the wires this spring as it was misfiring at that time. I thought I fixed the problem but it has come back again and now it's worse.

 

I switched the coil pack from cylinder 3/6 to cylinder 1/4 and it still came up misfire cylinder 6 so it can't be the coil pack. I had an old set of plug wires and changed the cylinder 6 wire and it did not help. I also have dual electrode plugs installed, they were done about 6 months ago.
It acted the same way about 3 months ago and a tank of gas, fuel injector cleaner and a new fuel filter it started running better. I put a new tank of gas and cleaner in today so we'll see if it clears up. I have checked all the vacuum hoses and don't see a bad one.
I'm thinking it's the injector and of course it's the one under the plenum but I'm about out of ideas.
This is my wife's truck and she is pregnant so I need to get this figured out. I appreciate all and any help.

 

You would be supprised that it may be somthing just as simple as a bad ground. Clean and/or replace the ground cable that goes to the battery cable at both ends. remove on both ends and clean the area where the cable makes contact. seems to be the fastest and easiest fix, if thats what it is. Happened to me. The mysterious miss then disappeard.
Jeff

 

Did you check the injector for number 6
Try using the "stethoscope" method a long screw driver and listen for clicking at the injector. Also check the resistance of the injector and see if it is within specs. Connect a noid light ( a 12 volt light bulb with 2 wires ) , to the injector connector and when you turn the engine over the bulb should flash mimicking the injector pulse.

 

I don't know how to get to the #6 injector without taking the top of the motor apart.
I put a new PCV valve in just trying to solve it the inexpensive way but that did not help.
I thought about running Seafoam through it but I'm not sure I want to use that stuff or not.
I'm running out of ideas. My check engine light was blinking and then went off and has been off all day. I might have to just fork over the money and have someone check it with a computer and compression test because I don't have the tools.

 

my service guy said the code for the check engine light was for a misfire in the cylinder 6 (0306 i presume). I have had to change the coil in the number 1 a while ago, where is the number 6 cylinder?

 

Thanks 98tacoma. seems as though there may be more trouble shooting here. As I replaced the 1/6 coil recently (about 2yrs ago at dealer). I guess if they go bad they can miss fire only one of the cylinders?? I'll start with plugs.

 

You have vaccum leaking in valves . Need to have heads rebuilt. Put pressure gauge on cylinder. Crank, with gauge in cylinder. Should drop after running

 

Remove wire from injector while running, if nothing happens, it's the valves no closing

 

Just went through a misfire on my 3.4. After doing a compression test, I found that my #5 cylinder wasn’t holding near the compression the rest were. Ended up being a burnt valve causing the misfire. Had the head taken off and valve replaced, all seems to be well now

 

This is my adventure in trying to find a misfire

https://www.tacomaworld.com/threads/lets-find-that-lost-cylinder-5-out-of-6-aint-bad-right.475084/

 

Does this miss firing noticeably effect the running performance of the engine?